Telephone system



June 10, 1941. w. MAI ET AL 2,244,914

TELEPHONE SYSTEM Filed Sept. 16, 1939 2 Sheets-Sheet 1 MWb cc [/1206 r 1 5mm EX I 43cc MWC we f 56dc2 1 WAL TER MA/ HERBEA7 R/Cf/TER M/VE/VTORS A TTOR/VE K June 10, 1941. 4 w. MAI ETAL I TELEPHONE -SYSTEM Filed Sept. 16. 1959 2 Sheets-Sheet 2 FIG}? Axed-$1] ATTOK/VEK Patented June 10, 1941 TELEPHONE SYSTEM Walter Mai, Berlin-Siemensstadt, and" Herbert Richter, Berlin-charlotten'burg, Germany, assignors to Fides' Gesel'lschaft furdie Ver-- waltung 11nd Verwertungvon gew'e'rblichcn Schutzrechten' mit beschrankter' Battling, Ber'- lin, Germany, a corporation of Germany Application September 16, 1939; Serial No. 295,242 In Germany September 2'7,v 1938' 5 Claims.

The present invention relates to a relay selector which on the coming into effect of a call impulse connects an incoming line with a free outgoing line.

Arrangements are known in which when a call is made the busy condition of all lines outgoing over the relay selectoris determined simultaneously and in which further, all free outgoing lines are, at the same time, prepared for seizing. Since the outgoing lines are multipled to the contacts of a plurality of relay selectors the danger arises that a number of incoming lines may be connected to one and the same outgoing line when simultaneous call impulses are efiec'tive on a number of relay selectors and the busy condition of theoutgoing lines at these relay selectors is determined at the same time. The object of the present invention is to prevent the undesired interconnection of a number of incoming lines using the simplest means and producing completely positive operation. The object is attained in that all test relays which on the coming into effect of a call impulse determine the engaged condition of the lines outgoing over the relay selectors, are controlled by two contact chains, of which one determines the series successi'cn in which the outgoing lines can be seized, while the second chain determines the series succession in which the various relay selectors are to'have access to the same outgoing line.

In the drawings an embodiment of the invention is shown. Figs. 1 and 2 taken together, with: Fig. '2' on the right of Fig. 1, show three relay selectorsfor connecting with idle outgoing trunk lines VLI, VL2 and VL3. The selector MWa is shown in full, while selectors MW?) and MWc are shown in part. All circuit details not completely necessary for the understanding of the invention, as well as the circuit of the connecting arrangements lying on either side of the relay selectors in the connecting path, are omitted.

At a connecting arrangement previous to the relay selector MWa positive potential is connected to the seizing conductor l and thus the circuit for the seizing relay Ca is completed. Relay Ca at its contacts a connects the slowto-operate relay Cal to the seizing conductor I. Further over contacts 40a to lca it connects negative potential to the high resistance windings l of relays Dal, DaZ, Da3, etc. The relays Da are the test relays which determine the con dition of the outgoing lines accessible over the relay selector MWa of which three lines VL-l to VL3 are shown.

If all three lines are free then the associated relay D'a' of the relay selector MWa operates but not the seizing relays Cl l, 012, Cl3. Only the relay Da'l can maintain its armature attracted and hold its contact dal' in the operated. condition since it opens contact Bdal' in the contact chain consisting of the contacts of all the test relays of the relay selector, and thus interrupts the energisi'n'g. circuit over the. en'ergising winding of the relays D'a2', Da'3, etc. associated with the other lines VLZ, VL3.

If the junction VLI is engagedthen the contact Sell controlled by it's seizing relay CH is opened and the relay Dal can accordingly not operate, and the relay Da'2 which tests the condition of the junction VLZ can. operate if the line is free, and at. contact lll'da2 open the energising circuit for the test relay Da3 arranged further along the line so that no test relay of another free outgoing line can remain energised.

The contact chain which in addition to the contacts Soc, Sec etc, consists of the contacts Sdal, lll'd'aZ. ll da 3, etc. of the test relays of the relay selector determines the series succession in which the outgoing line's accessible over the relay selector can be seized.

It is assumed that the junction VLl is free and accordingly relay Dal is energised. At contact l2d'al it connects its holding winding II and at contact l3da'l opens the holding circuit of the next test relay which has determined the free condition of the junction which it tests. Accordingly if this test relay, for example D112, although its energising circuit has been interrupted at contact Sdal, has already closed its contact M11112 and opened contact IlS'daZ it cannot maintain its armature attracted since the holding circuit is opened at contact l3dal.

Over the holding winding of the test relays the seizing impulses are transmitted to the individualoutgoing lines. In order not to seize all the free junction lines at the same time the seizi-ng impulse in the relay selector MWa is only transmitted to the associated junction after a delay. Ihis result is obtained due to the delayed operation of the auxiliary relay Cal connected by the seizing relay Ca. The delaying opera-tion is so arranged that the contacts of the relay are only operated when the testing operation is completed and when it has been determined which of the outgoing lines is to be used for the connection to be set up by means of the contact chain which controls the energising circuit of the test relays.

The provision of the junction arrangements on either side of the relay selector determine whether a special common switching through relay is necessary or not. In many cases it is sufiicient to provide a switching through stage in each of the access means branching from the incoming line to the individual outgoing line This switching stage, e, g. contacts lfidal, lldal in the access means to the line VLl, is closed by the test relay Dal before the seizing relay Cl of the outgoing line operates, since the seizing impulse, as already mentioned, is only transmitted to this line after a delay. When a switching through stage is sufficient in each of the indi-' vidual access means, the special switching through relay Pa shown in the drawings is'not necessary. Positive potential is then connected directly over contacts l8cal and the junction points I9, to the first'contact of a contact chain controlling the holding circuit of the test relays, and effects the energising of the seizing relay Cll in the circuit: contact l8cal, junction points I9, 20, contact lZdal. winding II of relay Dal, relay Cl l, The conductors serving for trunk calls are then switched through metallically as is indicated by the dotted lines.

When all outgoing lines in this arrangement are engaged, a buzzer is connected to the upper conductor serving for interexchange trafiic over the series contacts Zldal, 22da2, 23da3, 24cal, as an engaged signal for the calling station. At the same time positive potential is connected over the contacts 25dal, 26da2, 2'lda3 and the resistance 28 to the lower conductor.

When, however, switching through to the selected outgoing line e. g. VLI, must not occur before the energising of the seizing relay of this line, i. e. before the energising of relay CH, 2. special switching through relay Pa is provided.

On the first contact of the contact chain which controls the holding circuit for the test relays positive potential is connected over contact 29cal, the relay Pa and junction points 30, 20. In the two conductors serving for interexchange traific, switching through contacts 3 lpa and 3232a are then provided. If all outgoing lines are engaged none of the test relays Da is energised. The energising circuit for the switching through relay Pa is not completed. The engaged signal is connected over contact 3311a to the upper conductor and over resistance 34 and contact 3510a to the lower conductor.

Relay Cal which transmits the delayed seizing impulse to the selected outgoing line on its operation, disconnects the seizing relay Ca by opening contact 2cal andover contact 36cal locks up in a circuit extending over the seizing conductor I. Relay Ca restores and opens contacts a, a, etc. in the contact chain which controls the energising circuits of the test relays.

Relay Cll operating on the coming into efiect of the seizing impulse on the junction line VLl being taken into use, opens contact Sell and thus disconnects idle potential from the test conductor.

The case will now be considered in which all junction VLI, VL2, VL3 are free and calling impulses are transmitted simultaneously by all three relay selectors MWa, MWb, MWc. In addition to the relays Ca in the relay selector MWal the relays Cb and Co not shown of the discriminating selectors MWb and We are also energised. Simultaneously with contacts 40a to lea the contacts 310b, 380b, 390b, lllcb are closed in the energising circuits of the test relay Db of the relay selector MWb, and the contactsdlce, 42cc,

43.00 and A ice in the relay selector MWc. Since all three junctions are free the three test relays in each discriminating selector are energised.

The connecting together of a number of incoming lines in such a manner that the same outgoing line is seized at the associated relay selectors is now prevented by the provision of further contact chains controlling the test relays of the selector. object the determination of the series succession Each contact chain has as its in which the individual relay selectors will have access to one and the same outgoing line. Accordingly a contact chain is provided for each outgoing line which consists of contacts of those test relays of the associated discriminating selector which determine its seized condition. Thus the contact chain preventing a multiple seizing of the outgoing line VLl consists of contacts 'Sdal, lSdbl, lldcl; the contact chain which prevents the multiple seizing of the line VL2 consists of contacts 48da2, 49db2, 50dc2 and the contact chain which prevents the multiple seizing of the line VLS consists of contacts 5lda3, 52db3, 53603.

When the line VLl is free, all three discriminating selectors MWa, MW?) and MWc have their test relays operated. Relay Dal at contact GEdal disconnects positive potential from the energising winding I of relay Dbl which closes contact dfidbi again should this already have been opened. Also the relay Dcl cannot operate since positive potential is connected at contact 45dal.

At the discriminating selector MWb accordingly, contact S idb l is closed again should this already have been opened. Relay DbZ operates and by opening contact 49am prevents an energising of relay D02. The incoming line with which the discriminating selector is associated is thus connected with the outgoing line VL2.

In the discriminating selector MWc since the contacts 55dcl and 56dc2 are closed the test relay Dcfi operates. This discriminatingselector thereby connects itsincoming line with the outgoing line VL3.

We claim:

1. In a relay selecting switch having means for connecting any one of a plurality of incomingv lines to an idle one of a plurality of outgoing lines, a plurality of test relays for eachincominglineone for each outgoing line, a contact chain controlled by said relays and operated upon initiation of a call from one of said incoming lines to determine the series succession in which the outgoing lines may be seized and another contact chain controlled by said relays for determining the succession in which said selectors have access to the same outgoing line.

2. A relay selector such as claimed in claim 1 in which the first-chain includes a contact seton all the test relays of an incoming line, and the second chain includes contacts on corresponding test relays of each incoming line.

3. In a relay selector, an incoming line, a plurality of outgoing lines accessible thereto, a plurality of test relays individual to the incoming line one for each outgoing line, means for making certain of the outgoing lines busy, means respon-.

sive to the initiation of a call over said incoming line for completing circuits over all test relays.

associated with idle trunks, a chain of contacts controlled by said relays and operated when the relays are energized to open the circuits of all but one of said relays and to complete a locking circuit for that one relay, said chain of contacts arranged to insure a definite order of succession in which the idle outgoing lines may be seized.

4. A relay selecting system such as claimed in claim 1 in which there are holding circuits for each test relay, and a third chain of contacts controlled by said relays for controlling said holding circuits.

5. In a relay selecting system, a plurality of incoming lines, a relay selector for each line, a plurality of trunk lines accessible in common to said selectors, a series of test relays for each selector one for each trunk line, a chain circuit for all relays of one selector for providing a definite order of access by that selector of the trunk lines, a chain circuit for the relays of all selectors corresponding to the same trunk line for providing a definite order of access of the selectors to that trunk line, and means responsive to the initiation of each call over an incoming line for completing a circuit for each test relay associated with an idle trunk line.

WALTER, MAI. HERBERT RICHTER. 

